It is known that polymeric materials are subject to deterioration due to the action of heat, light and air, which cause loss of mechanical properties, discoloring and other undesired effects.
Various classes of compounds have been proposed for the stabilization of polymeric materials, principally against UV radiation of the solar light, such as for example benzophenones and benzotriazoles. These compounds confer to the polymers an acceptable stability, which is however not yet sufficient for the practical needs with reference to the fibers, films and raffia made of olefinic polymers.
Polyalkylpiperidine polymers, normally denominated HALS (Hindered Amine Light Stabilizers) are effective for stabilizing polymeric materials and many patents, such as U.S. Pat. No. 4,477,615 and U.S. Pat. No. 4,086,204, describe the preparation and use thereof and the obtained results.
However, said known stabilizers are not completely satisfying and the polymeric materials are still subject to the undesired deterioration due to the action of heat, light and air, with the above mentioned negative consequences. Besides, a further disadvantage of the stabilizer compounds according to the known art is that their synthesis requires the employment of expensive starting compounds which make their preparation costly.
Therefore, there is the need to make available to the industry polypiperidine compounds which can impart to polymeric materials, in particular to polyolefins, a high stability towards photodegradation and oxidative action of the air.